Bio-ethylene Production

Technologies for industry and agriculture

The bio-ethylene is a so-called drop-in chemical, since it can replace directly the ethylene produced from a fossil-based feedstock in the existing industrial facilities. Because of concerns about the fossil resources depletion and the greenhouse gas emissions effects, the attention has recently shifted towards the use of this bio-resource. Indeed it can be produced by the catalytic dehydration of bio-ethanol i.e. ethanol derived from renewable feedstock such as biomass carbohydrates. 1st generation and 2nd generation bio-ethanol can in principle be considered as intermediate for bio-ethylene production, the former route is fully commercial, while the latter is at pre-commercial stage, TRL 8-9.

There are others potential (less explored) alternatives that would avoid the competition between different uses of bio-ethanol, i.e. as biofuel or chemical intermediate for subsequent productions. For example, bio-dimethyl ether (bio-DME), obtained from syngas, coming from conversion of ligno-cellulosic biomass, can be used as basic chemical for bio-ethylene. Alternatively bio-ethylene can be also sustainably and efficiently produced photosynthetically from CO2, using engineered cyanobacteria. However these technologies are currently under development and the resulting bio-ethylene cost is still high.

Bio-ethylene is mainly linked to the production of two biopolymers, bio-PE and bio-PET, which are leaders in the production of plastic bottles. Their production processes use this chemical as building block, directly and via mono ethylene glycol respectively. The global production capacity of bio-ethylene destined to bio-PE accounts for 200.000 t/y. This amount is currently produced in Brazil by Braskem and has remained stable since 2011. Instead bio-ethylene production for bio-MEG has been slowed down. The lack of further developments in bio-ethylene production has been determined by the low crude oil price marking the last years. Indeed it led to cancellation and postponement of several projects as well as the shutdown of some production plants that have been planned/built in the previous years

29-07-2022

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